Tilapia mossambica streptococcus agalactiae oral attenuated freeze-dried vaccine

Abstract

The invention discloses a tilapia mossambica streptococcus agalactiae oral attenuated freeze-dried vaccine and its preparation method. According to the invention, tilapia mossambica streptococcus agalactiae attenuated bacterial strain YM001 is performed with steps of enlarge cultivation, thalline collection and freeze-drying preparation to obtain the oral attenuated vaccine. The immunizing dose, immunization program and a vaccine usage method of the vaccine can be determined through tests. The immune efficacy, security and maneuverability of the vaccine can be detected and confirmed through field tests, the result shows that the vaccine has the advantages of high protection effectiveness, good security, convenient usage and low cost, the vaccine can be used for preventing tilapia mossambica streptococcus agalactiae, and has high business value.

Description

technical field [0001] The invention relates to a vaccine for preventing tilapia agalactiae streptococcosis, in particular to the bacterial strain used in the vaccine, the preparation of the vaccine, the immunization dosage, the immunization procedure and the immunization method. Background technique [0002] Streptococcus agalactiae is a common pathogenic bacteria in aquaculture, which can harm different species of fish, such as tilapia, sea bass, pomfret, sea bream, grouper, etc. Among them, tilapia streptococcus agalactiae is the most common Severe (Duremdez et al, 2004; Jafar et al, 2008; Amal et al, 2012). The disease causes extremely high mortality and causes huge economic losses to the aquaculture industry every year (Wang et al, 2014). China is the largest tilapia country in the world, and its output accounts for about 45% of the world's total output. For six consecutive years from 2009 to 2014, streptococcal disease broke out in a large area of ​​tilapia aquacultu...

AI Technical Summary

Problems solved by technology

Two methods have been reported to prepare the attenuated Streptococcus agalactiae vaccine: 1) Pridgeon screened out the attenuated Streptococcus agalactiae strain by continuously increasing the concentration of sparfloxain. The virulence is more likely to be strengthened under the stress of no antibiotics, and injection is used for immunization (Pridgeon et al, 2013); 2) Huang used live attenuated Salmonella typhimurium as a vector to express the DNA of Streptococcus agalactiae surface antigen (Sip) Attenuated vaccine, the attenuated strain prepared by this method has poor stability, low immune response intensity, and the immune protection period is only 7 days (Huang et al, 2014)

Continuous passage in vitro is a classic method of attenuating bacterial virulence. The stability and immunogenicity of the obtained attenuated strains are significantly better than those obtained by gene knockout or antibiotic stress screening. The disadvantage is that the number of passages is often large. so time consuming

So far, there are no reports about natural passage of attenuated strains of Streptococcus agalactiae in fish or other hosts

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